Halogenated terpolymers of isobutylene, diolefin monomer and styrenic monomer

ABSTRACT

A halogenated butyl polymer having improved properties, the butyl polymer derived from a monomer mixture comprising a C 4  to C 8  monoolefin monomer, a C 4  to C 14  multiolefin monomer and a styrenic monomer with a catalyst system to produce the butyl polymer. The improved properties include faster cure, higher maximum torque, higher delta torque, relatively stable modulus over time, improved hot air aging properties and improved aged flexure properties. These improved properties are believed to result from direct interaction between the styrenic moieties in the polymer backbone with a crosslinking agent added to vulcanize the halogenated butyl rubber.

[0001] In one of its aspects, the present invention relates to ahalogenated butyl polymer. In another of its aspects, the presentinvention relates to a process for production of a butyl polymer.

[0002] Butyl polymer or rubber is well known in the art, particularly inits application in the production of tires.

[0003] Further, the use of halogenated butyl rubbers is known since suchrubbers have particularly advantageous adhesion behaviour, flexuralstrength, service life and impermeability to air and water.

[0004] Despite this, there is room for improvement. Specifically, asmanufacturer warranties for tires continue to increase in term, there isan ongoing desire and need to extend the useful service life of thetire. This projects into a need to improve the properties of thecomponents of the tire, including the rubber (e.g., halogenated butylrubber) components. This is becoming especially important in tireretreading applications.

[0005] Thus, there is a continuing need in the art for halogenated butylrubbers, inter alia, having improved curing and/or aging properties.

[0006] It is an object of the present invention to provide a novelhalogenated butyl polymer.

[0007] It is another object of the present invention to provide a novelprocess for producing a halogenated butyl polymer.

[0008] It is yet another objection of the present invention to provide anovel vulcanizate derived from a halogenated butyl polymer.

[0009] Accordingly, in one of its aspects, the present inventionprovides a halogenated butyl polymer having improved curing and/or agingproperties, the butyl polymer derived from a monomer mixture comprisinga C₄ to C₈ monoolefin monomer, a C₄ to C₁₄ multiolefin monomer and astyrenic monomer.

[0010] In another of its aspects, the present invention provides aprocess for preparing a halogenated butyl polymer having improved curingand/or aging properties, the process comprising the steps of:

[0011] contacting a monomer mixture comprising a C₄ to C8 monoolefinmonomer, a C₄ to C₁₄ multiolefin monomer and a styrenic monomer with acatalyst system to produce a terpolymer; and

[0012] halogenating the terpolymer to produce the halogenated butylpolymer.

[0013] In another of its aspects, the present invention provides avulcanizate derived from a vulcanizable mixture comprising: ahalogenated butyl polymer derived from a monomer mixture comprising a C₄to C₈ monoolefin monomer, a C₄ to C₁₄ multiolefin monomer and a styrenicmonomer; a filler; and a vulcanization agent.

[0014] Thus, the present invention relates to butyl rubber polymers. Theterms “butyl rubber”, “butyl polymer” and “butyl rubber polymer” areused throughout this specification interchangeably and each is intendedto denote polymers prepared by reacting a monomer mixture comprising aC₄ to C₈ monoolefin monomer, a C₄ to C₁₄ multiolefin monomer and astyrenic monomer.

[0015] It has been surprisingly and unexpectedly discovered thathalogenating a terpolymer derived from a monomer mixture comprising a C₄to C₈ monoolefin monomer, a C₄ to C₁₄ multiolefin monomer and a styrenicmonomer results in a polymer having improved properties compared to apolymer produced by halogenating a copolymer derived from a monomermixture comprising a C₄ to C₈ monoolefin monomer and a C₄ to C₁₄multiolefin monomer. The improved properties include faster cure, highermaximum torque, higher delta torque, relatively stable modulus overtime, improved hot air aging properties and improved aged flexureproperties. These improved properties are believed to result from directinteraction between the styrenic moieties in the polymer backbone with acrosslinking agent added to vulcanize the halogenated butyl rubber.

[0016] Embodiments of the present invention will be described withreference to the accompanying drawings, in which:

[0017]FIGS. 1 and 2 illustrate the (Raman infrared) R.I. and(ultraviolet) U.V (256 nm) traces of the GPC chromatogram of terpolymersin accordance with the present invention;

[0018]FIG. 3 illustrates a depiction of various bromine containingstructures;

[0019]FIG. 4 illustrates the cure behaviour of a conventional polymer;

[0020]FIGS. 5 and 6 illustrate the cure behaviour of terpolymers inaccordance with the present invention;

[0021]FIGS. 7 and 8 illustrate hot air aging properties of terpolymersin accordance with the present invention.

[0022] Thus, the present terpolymers are derived and the present processrelates to the use of a monomer mixture comprising a C₄ to C₈ monoolefinmonomer, a C₄ to C₁₄ multiolefin monomer and a styrenic monomer.

[0023] Preferably, the monomer mixture comprises from about 80% to about99% by weight C₄ to C₈ monoolefin monomer, from about 0.5% to about 5%by weight C₄ to C₁₄ multiolefin monomer and from about 0.5% to about 15%by weight styrenic monomer. More preferably, the monomer mixturecomprises from about 85% to about 99% by weight C₄ to C₈ monoolefinmonomer, from about 0.5% to about 5% by weight C₄ to C₁₄ multiolefinmonomer and from about 0.5% to about 10% by weight styrenic monomer.Most preferably, the monomer mixture comprises from about 87% to about94% by weight C₄ to C₈ monoolefin monomer, from about 1% to about 3% byweight C₄ to C₁₄ multiolefin monomer and from about 5% to about 10% byweight styrenic monomer.

[0024] The preferred C₄ to C₈ monoolefin monomer may be selected fromthe group comprising isobutylene,2-methylpropene-1,3-methylbutene-1,4-methylpentene-1,2-methylpentene-1,4-ethylbutene-1,4-ethylpentene-1and mixtures thereof. The most preferred C₄ to C₈ monoolefin monomercomprises isobutylene.

[0025] The preferred C₄ to C₁₄ multiolefin monomer may be selected fromthe group comprising isoprene, butadiene-1,3,2,4-dimethylbutadiene-1,3,piperyline, 3-methylpentadiene-1,3,hexadiene-2,4,2-neopentylbutadiene-1,3,2-methlyhexadiene-1,5,2,5-dimethlyhexadiene-2,4,2-methylpentadiene-1,4,2-methylheptadiene-1,6,cyclopentadiene, methylcyclopentadiene, cyclohexadiene,1-vinyl-cyclohexadiene and mixtures thereof. The most preferred C₄ toC₁₄ multiolefin monomer comprises isoprene.

[0026] The preferred styrenic monomer may be selected from the groupcomprising p-methylstyrene, styrene, α-methylstyrene, p-chlorostyrene,p-methoxystyrene, indene (including indene derivatives) and mixturesthereof. The most preferred styrenic monomer may be selected from thegroup comprising styrene, p-methylstyrene and mixtures thereof.

[0027] As stated hereinabove, the butyl polymer is halogenated.Preferably, the butyl polymer is brominated or chlorinated. Preferably,the amount of halogen is in the range of from about 0.1 to about 8%,more preferably from about 0.5% to about 4%, most preferably from about1.5% to about 3.0%, by weight of the polymer.

[0028] The halogenated butyl polymer may be produced by halogenating apreviously produced butyl polymer derived from the monomer mixturedescribed hereinabove. The manner by which the butyl polymer is producedis conventional and within the purview of a person of ordinary skill inthe art. Thus, the process for producing the butyl polymer may beconducted at a temperature conventional in the production of butylpolymers (e.g., in the range of from about −100° C. to about +50° C.;usually less than −90° C.) in the presence of a conventional catalyst(e.g., aluminum trichloride). The butyl polymer may be produced in aconventional manner, by polymerization in solution or by a slurrypolymerization method. Polymerization is preferably conducted insuspension (the slurry method). For more information on the productionof butyl rubber, see, for example, any of the following:

[0029] 1. Ullmann's Encyclopedia of Industrial Chemistry (Fifth,Completely Revised Edition, Volume A23; Editors Elvers et al.).

[0030] 2. “Cationic Polymerization of Olefins: A Critical Inventory” byJoseph P. Kennedy (John Wiley & Sons, Inc. ©1975); and

[0031] 3. “Rubber Technology” (Third Edition) by Maurice Morton, Chapter10 (Van Nostrand Reinhold Company ©1987).

[0032] The butyl polymer may then be halogenated in a conventionalmanner. See, for example, U.S. Pat. No. 5,886,106. Thus, the halogenatedbutyl rubber may be produced either by treating finely divided butylrubber with a halogenating agent, such as chlorine or bromine,preferably bromine, or by producing brominated butyl rubber by intensivemixing, in a mixing apparatus, of brominating agents such asN-bromosuccinimide with a previously made butyl rubber. Alternatively,the halogenated butyl rubber may be produced by treating a solution or adispersion in a suitable organic solvent of a previously made butylrubber with corresponding brominating agents. See, for more detail,Ullmann's Encyclopedia of Industrial Chemistry (Fifth, CompletelyRevised Edition, Volume A23; Editors Elvers et al.) and/or “RubberTechnology” (Third Edition) by Maurice Morton, Chapter 10 (Van NostrandReinhold Company © 1987). The amount of halogenation during thisprocedure may be controlled so that the final terpolymer has thepreferred amounts of halogen described hereinabove. The specific mode ofattaching the halogen to the polymer is not particularly restricted andthose of skill in the art will recognize that modes other than thosedescribed above may be used while achieving the benefits of theinvention.

[0033] The present halogenated butyl rubber may be used for theproduction of vulcanized rubber products. For example, usefulvulcanizates may be produced by mixing the halogenated butyl rubber withcarbon black and/or other known ingredients (additives) and crosslinkingthe mixture with a conventional curing agent in a conventional manner.

[0034] Embodiments of the present invention will be illustrated withreference to the following Examples, which should not be use to construeor limit the scope of the present invention. In the Examples, “pbw”means parts by weight and “phr” means parts by weight per 100 parts byweight rubber or polymer product.

EXAMPLES 1-7

[0035] In the Examples, isobutylene (1B, Matheson, 99%) and methylchloride (MeCl, Matheson, 99%) were used as received. Isoprene (IP,Aldrich 99.9%), p-methyl styrene (p-MeSt, Aldrich 97%) and styrene (St,Aldrich 99%) were passed through a t-butyl catechol inhibitor removerprior to usage. Aluminum trichloride (Aldrich 99.99%), stearic acid(NBS, technical grade) and zinc oxide (Midwest Zinc Co., technicalgrade) were used as received.

[0036] All polymerizations were carried out in an MBraun MB™ 150B-G-Idry box.

[0037] A saturated catalyst solution was prepared by combiningapproximately Ig of AlCl₃ with 100 mL of MeCl. This solution was stirredfor a period of 30 minutes at a temperature of −30° C.

[0038] IB, IP, p-MeSt and St were charged, according to theconcentrations reported in Table 1, into a 2 litre baffled glass reactorwhich was equipped with a stainless steel stirrer and a thermocouple.The reactor containing the monomers was cooled to −95° C., after which10 mL of catalyst solution was introduced into the reactor. Thepolymerizations were carried out until a maximum temperature wasreached. The polymerizations were terminated with the addition to thereactor of 10 mL of ethanol. The polymer was recovered by dissolving inhexane, followed by ethanol coagulation. The polymer was then dried in avacuum oven at 40° C. until a constant weight was reached.

[0039] As will be apparent, neither p-MeSt nor St were used inExample 1. Accordingly, this Example is provided for comparativepurposes only and is outside the scope of the invention.

[0040] Molecular weight and molecular weight distribution weredetermined by GPC equipped with an ultraviolet (U.V.) and Raman infrared(R.I.) detector using 6 Waters Ultrastyragel columns (100, 500, 10³,10⁴, 10⁵ and 10⁶ Å), thermostated at 35° C. The mobile phase was THF at1 mL/min. flow rate. Flow rate was monitored by the use of elementarysulfur as internal marker. The instrument was calibrated with 14 narrowMWD PS standards. Molecular weight averages were calculated using theUniversal Calibration Principle using K_(PSt)=1.12×10⁻⁴ dl/g,α_(PSt)=0.725, K_(PIB)=2.00×10⁴ dl/g and α_(PiB)=0.67. Calcium stearate,ESBO and EXO values were determined by FTIR. 500 MHz ¹H NMR spectra wereobtained in a conventional manner and the evaluation of the spectraobtained was done in a conventional manner—see, for example, (i) Chu etal., Macromolecules 18, 1423 (1985), and (ii) Chu et al., Rubber Chem.Technol. 60, 626 (1987). Bromine content was determined by Oxygen FlaskCombustion and Tg values were determined by DSC. Hot air aging studieswere carried out according to ASTM-D573-81.

[0041]FIGS. 1 and 2 illustrate the R.I. and U.V. (256 nm) traces of theGPC chromatogram of a p-MeSt terpolymer (Example 4) and a St terpolymer(Example 7), respectively. Comparison of the R.I. and U.V. tracesprovides information about the compositional homogeneity of the polymeras a function of molecular weight. The R.I. signal is proportional tothe total mass of the polymer chain. The U.V signal is proportional tothe number of aromatic monomer units incorporated into the chain, sinceU.V. absorption of 1B and IP units are negligible at 256 nm compared tothat of the aromatic ring.

[0042] The R.I. and U.V. traces of the pMeSt terpolymer show nearcomplete overlapping. The U.V/R.I. ratio, which is proportional to thep-MeSt content of the given molecular weight fraction, is substantiallyconstant over the entire molecular weight range. These results confirmthat the reactivity of IB and p-MeSt is very similar toward theisobutylene capped growing cation.

[0043] In contrast, the St terpolymer exhibits non-overlapping U.V. andR.I. traces. The U.V./R.I. ratio, i.e., the styrene content of thepolymer increases by a factor of about four as molecular weightdecreases (elution volume increases), which is an indication that Stacts as a chain transfer agent and has lower reactivity toward the IBcapped growing cation than IB.

[0044] The foregoing analysis confirms the formation of a randomcopolymer.

[0045] Each batch of polymer product produced was brominated in thefollowing manner.

[0046] The polymer product was dissolved in hexane to produce a polymercement to which 0.08 phr octylated diphenylamine (ODPA) and 0.017 phrIrganox™ 1010 was added. Thereafter, the cement was solvent stripped andmill dried.

[0047] The resulting homogeneous rubber was once again cut into piecesand redissolved in hexane. The so-produced polymer cement was thentransferred to a 12 litre baffled reactor equipped with a mechanicalstirrer and two syringe ports. The cement container was rinsed withhexane and dichloromethane. Water was then added to the reactor and themixture was stirred for several minutes.

[0048] Bromination of the polymer product was started by injecting theappropriate amount of bromine into the reactor. After 4 minutes ofreaction time, the reaction was terminated by the injection of causticsolution (6.4 wt % NaOH). The mixture was allowed to stir for anadditional 10 minutes and a stabilizer solution containing 0.25 phrepoxidized soybean oil (ESBO), 0.02 phr ODPA and 0.003 phr Irganox™ 1076was then added to the mixture. The brominated rubber mixture was thenwashed three times after which additional ESBO (0.65 phr) and calciumstearate (1.5 phr) were added to the cement prior to steam stripping.The polymer was finally dried on a hot mill.

[0049] Bromine concentration, rubber concentration (solids), watercontent and reaction time were all kept constant. During bromination, 30vol % dichloromethane was used as a polar co-solvent in order to obtainimproved control over the extent of reaction and, thereby, to obtain thesame concentration of brominated structures (approximately 1.0 mol %) inall brominated polymer products. Stabilizer and antioxidant levels ofthe brominated terpolymers were kept constant. Calcium stearate levelwas set at 1.5 phr and ESBO level at 0.9 phr.

[0050] Composition of the brominated terpolymers, determined by 500 MHzHNMR, is reported in Table 2. The p-MeSt and St content determinedbefore and after bromination are substantially consistent with oneanother. According to the results, the amount of primary brominatedstructures was lower in the terpolymer than in the control and decreasedwith increasing p-MeSt or St content. This is believed to be anindication that the aromatic ring underwent bromination in addition tothe 1,4-IP enchainments. The presence of a brominated aromatic ring wasestimated from a mass balance: total bromine content of the samplesminus the amount of bromine attached to the 1,4-IP units. The totalbromine content of the samples was determined by oxygen flaskcombustion. Further, the amount of bromine attached to the 1,4-IP unitswas calculated from the HNMR results. Specifically, the calculation wasderived from the sum of bromine containing structures:Exo.+Rearr.Exo.+Endo.+hydrobrominated—see FIG. 3 for a depiction ofthese various bromine containing structures. The results are reported inTable 3.

[0051] With reference to Table 3, the two values for bromine content arereasonably matched in Example 2, indicating that the bromination of thearomatic ring is negligible. With reference to Examples 3 and 4,respectively, the two values for bromine content deviate indicating thatthe aromatic ring underwent bromination. The deviation between the twovalues is even more pronounced in the case of the styrene terpolymers(i.e., Examples 5-7). This is not surprising since, from a sterichinderance viewpoint, the more accessible para-position is not blockedin the case of styrene, and the ortho and para orienting affect of thealkyl group (polymer backbone).

[0052] For each Example, a gum vulcanizate was prepared by adding 1 phrof stearic acid and 5 phr of zinc oxide to the brominated polymer on amill set to 40° C. (i.e., no filler or oil was used duringvulcanization). Cure behaviour was determined by ODR Monsanto Rheometer(3 degree arc, 166° C.). Full (6×6 inches) and half sized (3×3 inches)macro sheets were prepared from these compounds by curing the compoundat 166° C. for 30 minutes.

[0053]FIGS. 4, 5 and 6 show the cure behaviour of the polymers ofExamples 1 (control), 2 (low p-MeSt content terpolymer) and 6 (medium Stcontent terpolymer), respectively. Cure time and torque values obtainedfor all the compounds are listed in Table 4.

[0054] According to the rheometry charts, the rubber produced in Example1 shows a large trough or long induction period before the onset ofcuring. Specifically, the copolymer produced in Example 1 reaches a Tc50point (half cured state) in approximately 13 minutes and a Tc90 point inapproximately ˜20 minutes. On the other hand, the terpolymers producedin Examples 2 (low p-MeSt content terpolymer) and 6 (medium St contentterpolymer) possess narrower torque curves and are observed to reachtheir Tc50 point in less than half the time in spite of the fact thatthe Examples 2 and 6 terpolymers contained 10-35% less Exo than theExample 1 copolymer. This is evidence that the aromatic rings take partin the curing reaction.

[0055] The Mh and Mh-Ml values of the terpolymers produced in Examples 2(low p-MeSt content terpolymer) and 6 (medium St content terpolymer)decreased with increasing p-MeSt or St content due to the decreasing Exocontent. However, the obtained torque values were at least the same oreven higher than that of the control. The most meaningful comparison canbe made by comparing the delta torque values of the Example 1 copolymer(Exo=0.97 mol %) with the Example 2 terpolymer (Exo=0.87 mol %,p-MeSt=2.69 mol %) and with the Example 6 terpolymer (Exo=0.85 mol %,St=1.81). By comparing the delta torque values, the effect of Mooney canbe accounted for. According to the results reported in Table 4, bothterpolymers gave higher delta torque values (14.0 dNm for Example 2 and12.4 dNm for Example 6) than Example 1 (10.8 dNm). This difference againis evidence that the aromatic rings do participate in the crosslinkingreaction.

[0056] In each of the Examples, the rubber was cured at 166° C. for 30minutes. The cured sheets were placed at room temperature for a periodof sixteen hours prior to cutting them into tensile test piecesaccording to standard test methods (ASTM D412-68). Each vulcanizate wassubjected to hot air aging tests (ASTM D573-81) under two differentconditions: 120° C. for 168 hours and 140° C. for 168 hours.

[0057] The hot air aging test results for the rubbers produced inExamples 1-3 and 5-7 are reported in Table 5. Further, FIG. 7illustrates the modulus at 100% elongation. Unaged terpolymers showapproximately 15% higher modulus over the control, which is consistentwith the measured higher torque values. The 100% modulus of the controlsample decreased by about 50% upon 168 hours hot air aging at 140° C.The terpolymers displayed a better resistance to aging: 100% modulusdecreased only by about 25%. FIG. 8 illustrates the modulus at 300%elongation before and after hot air aging for 168 hrs at 140° C. The300% modulus of the copolymer of Examples shows a decrease of 36% uponaging. In contrast, 300% modulus of the terpolymers decreased only byabout 2-5%.

[0058] Table 5 also summarizes the unaged stress strain results of theSt terpolymers and the results of the limited hot air aging studycarried out using the low St content terpolymer (Example 5). Here againthe modulus of the terpolymers is somewhat higher than that of thecontrol. The 100% modulus of the St terpolymer decreased by 30% and the300% modulus by 16% as a result of 168 hrs/140° C. hot air aging,indicating a better aging resistance over the copolymer of Example 1.

[0059] While the present invention has been described with reference topreferred and specifically exemplified embodiments, it will of course beunderstood by those of skill in the art that various modifications tothese preferred and exemplified embodiments may be made without theparting from the spirit and scope of the invention.

[0060] All publications, patents and patent applications referred toherein are incorporated by reference in their entirety to the sameextent as if each individual publication, patent or patent applicationwas specifically and individually indicated to be incorporated byreference in its entirety. TABLE 1 Ex- am- [p-MeSt]¹ [St]¹ Mw, Mw/ [IP][p-MeSt]² [St]² ple (mol/L) (mol/L) ×10³ Mn (mol %) (mol %) (mol %) 1 —— 474 4.3 1.37 — — 2 0.055 — 440 2.9 1.26  2.63 — 3 0.11  — 375 2.9 1.12 5.3  — 4 0.22  — 400 2.2 0.86 10.6  — 5 — 0.055 580 4.2 1.24 — 0.83 6 —0.11  540 4.6 1.15 — 1.71 7 — 0.22  475 4.4 1.00 — 3.58

[0061] TABLE 2 Example 1 2 3 4 5 6 7 Before Bromination 1,4-IP (mol %)1.46 1.26 1.12 0.86 1.24 1.15 1 p-MeSt (mol %) — 2.63 5.3  10.6 — — — St(mol %) — — — — 0.83 1.71 3.6 After Bromination p-MeSt (mol %) — 2.695.29 11.3 — — — St (mol %) — — — — 0.97 1.81 4.05 1,4-IP (mol %) 0.390.21 0.16 0 0.44 0.3  0.3 Exo (mol %) 0.97 0.87 0.79 0.63 0.71 0.85 0.7Endo (mol %) 0.05 0.04 0.04 0.03 0.04 0.05 0.03 Endo CDB (mol %) 0.030.02 0.02 0.02 0.02 0.03 0.03 Total primary (mol %) 1.05 0.93 0.85 0.680.77 0.93 0.76

[0062] TABLE 3 pMeSt St Br Content from Br Content by Oxy. Example (mol%) (mol %) HNMR (mol %) Flask (mol %) 1 — — 1.02 1.16 2  2.69 — 1.021.04 3  5.29 — 0.95 1.13 4 11.26 — 0.84 1.33 5 — 0.97 0.78 1.3  6 — 1.810.9  1.49 7 — 4.05 0.73 1.54

[0063] TABLE 4 Example 1 2 3 4 5 6 7 Exo (mol %)  0.97  0.87  0.79 0.63 0.71  0.85  0.7  pMeSt (mol %) —  2.69  5.29 11.26 — — — St (mol %) — —— —  0.97  1.81  4.05 Scorch 01 (min.) 10.26  2.71  2.89 4.24  4.84 3.63  4.18 Tc50 (min.) 13.36  4.03  4.12 5.78  6.59  5.02  5.77 Tc90(min.) 21.31  6.74 10.25 20.91  9.69 10.75  9.71 Mh (dNm) 18.57 22.4818.79 17.98 18.35 18.81 20.69 Ml (dNm)  7.77  8.51  6.35 7  8.97  6.47 8.4  Delta Torque (dNm) 10.81 13.96 12.43 10.98  9.37 12.35 12.29

[0064] TABLE 5 Example 1 2 3 5 6 7 Unaged Modulus @ 0.33 0.38 0.37 0.390.42 0.4 100% (MPa) Modulus @ 0.45 0.56 0.52 0.56 0.6 0.63 300% (MPa)Ultimate 3.5 2.1 2.7 4.1 4 3.4 Tensile (MPa) Ultimate 1055 910 1020 965880 850 Elongation (%) Hardness Shore 23 26 28 25 24 25 A2 (pts.) Agedin air, 168 hours @ 120° C. Modulus @ 0.36 0.41 0.4 — — — 100% (MPa)Modulus @ 0.67 0.75 0.72 — — — 300% (MPa) Ultimate 2.6 1.9 1.9 — — —Tensile (MPa) Ultimate 670 570 595 — — — Elongation (%) Hardness Shore26 28 28 — — — A2 (pts.) Aged in air, 168 hours @ 140° C. Modulus @ 0.170.3 0.29 0.27 — — 100% (MPa) Modulus @ 0.29 0.53 0.51 0.47 — — 300%(MPa) Ultimate 1.8 2.1 2.2 2.8 — — Tensile (MPa) Ultimate 805 670 725850 — — Elongation (%) Hardness Shore 23 27 26 21 — — A2 (pts)

What is claimed is:
 1. A halogenated butyl polymer having improvedcuring and/or aging properties, the butyl polymer derived from a monomermixture comprising a C₄ to C₈ monoolefin monomer, a C₄ to C₁₄multiolefin monomer and a styrenic monomer with a catalyst system toproduce the butyl polymer.
 2. The halogenated butyl polymer defined inclaim 1, wherein the C₄ to C₈ monoolefin monomer may be selected fromthe group comprising isobutylene,2-methylpropene-1,3-methylbutene-1,4-methylpentene-1,2-methylpentene-1,4-ethylbutene-1,4-ethylpentene-1and mixtures thereof.
 3. The halogenated butyl polymer defined in claim2, wherein the C₄ to C₈ monoolefin monomer comprises isobutylene.
 4. Thehalogenated butyl polymer defined in claim 3, wherein the C₄ to C₁₄multiolefin monomer is selected from the group comprising isoprene,butadiene-1,3,2,4-dimethylbutadiene-1,3, piperyline,3-methylpentadiene-1,3,hexadiene-2,4,2-neopentylbutadiene-1,3,2-methlyhexadiene-1,5,2,5-dimethlyhexadiene-2,4,2-methylpentadiene-1,4,2-methylheptadiene-1,6,cyclopentadiene, methylcyclopentadiene, cyclohexadiene,1-vinyl-cyclohexadiene and mixtures thereof.
 5. The halogenated butylpolymer defined in claim 4, wherein the C₄ to C₁₄ multiolefin monomercomprises isoprene.
 6. The halogenated butyl polymer defined in claim 1,wherein the styrenic monomer is selected from the group comprisingp-methylstyrene, styrene, α-methylstyrene, p-chlorostyrene,p-methoxystyrene and mixtures thereof.
 7. The halogenated butyl polymerdefined in claim 5, wherein the styrenic monomer comprises a memberselected from the group comprising styrene, p-methylstyrene and mixturesthereof.
 8. The halogenated butyl polymer defined in claim 1, whereinthe monomer mixture comprises from about 80% to about 99% by weight C₄to C₈ monoolefin monomer, from about 0.5% to about 5% by weight C₄ toC₁₄ multiolefin monomer and from about 0.5% to about 15% by weightstyrenic monomer.
 9. The halogenated butyl polymer defined in claim 8,wherein the monomer mixture comprises from about 85% to about 99% byweight C₄ to Cs monoolefin monomer, from about 0.5% to about 5% byweight C₄ to C₁₄ multiolefin monomer and from about 0.5% to about 10% byweight styrenic monomer.
 10. The halogenated butyl polymer defined inclaim 9, wherein the monomer mixture comprises from about 87% to about94% by weight C₄ to C₈ monoolefin monomer, from about 1% to about 3% byweight C₄ to C₁₄ multiolefin monomer and from about 5% to about 10% byweight styrenic monomer.
 11. The halogenated butyl polymer defined inclaim 1, wherein the polymer is brominated.
 12. The halogenated butylpolymer defined in claim 1, wherein the polymer is chlorinated.
 13. Thehalogenated butyl polymer defined in claim 1, wherein the amount ofhalogen is in the range of from about 0.1 to about 8% by weight of thepolymer.
 14. The halogenated butyl polymer defined in claim 13, whereinthe amount of halogen is in the range of from about 0.5 to about 4% byweight of the polymer.
 15. The halogenated butyl polymer defined inclaim 14, wherein the amount of halogen is in the range of from about1.5 to about 3% by weight of the polymer.
 16. A process for preparing ahalogenated butyl polymer having improved curing and/or agingproperties, the process comprising the steps of: contacting a monomermixture comprising a C₄ to C₈ monoolefin monomer, a C₄ to C₁₄multiolefin monomer and a styrenic monomer with a catalyst system toproduce a terpolymer; and halogenating the terpolymer to produce thehalogenated butyl polymer.
 17. The process defined in claim 16, whereinthe C₄ to C8 monoolefin monomer may be selected from the groupcomprising isobutylene,2-methylpropene-1,3-methylbutene-1,4-methylpentene-1,2-methylpentene-1,4-ethylbutene-1,4-ethylpentene-1,beta-pinene and mixtures thereof.
 18. The process defined in claim 17,wherein the C₄ to C₈ monoolefin monomer comprises isobutylene.
 19. Theprocess defined in claim 16, wherein the C₄ to C₁₄ multiolefin monomeris selected from the group comprising isoprene,butadiene-1,3,2,4-dimethylbutadiene-1,3, piperyline,3-methylpentadiene-1,3,hexadiene-2,4,2-neopentylbutadiene-1,3,2-methlyhexadiene-1,5,2,5-dimethlyhexadiene-2,4,2-methylpentadiene-1,4,2-methylheptadiene-1,6,cyclopentadiene, methylcyclopentadiene, cyclohexadiene,1-vinyl-cyclohexadiene and mixtures thereof.
 20. The process defined inclaim 19, wherein the C₄ to C₁₄ multiolefin monomer comprises isoprene.21. The process defined in claim 16, wherein the styrenic monomer isselected from the group comprising p-methylstyrene, styrene,α-methylstyrene, p-chlorostyrene, p-methoxystyrene and mixtures thereof.22. The process defined in claim 21, wherein the styrenic monomercomprises a member selected from the group comprising styrene,p-methylstyrene and mixtures thereof.
 23. The process defined in claim16, wherein the monomer mixture comprises from about 80% to about 99% byweight C₄ to C₈ monoolefin monomer, from about 0.5% to about 5% byweight C₄ to C₁₄ multiolefin monomer and from about 0.5% to about 15% byweight styrenic monomer.
 24. The process defined in claim 23, whereinthe monomer mixture comprises from about 85% to about 99% by weight C₄to C₈ monoolefin monomer, from about 0.5% to about 5% by weight C₄ toC₁₄ multiolefin monomer and from about 0.5% to about 10% by weightstyrenic monomer.
 25. The process defined in claim 24, wherein themonomer mixture comprises from about 87% to about 94% by weight C₄ to C₈monoolefin monomer, from about 1% to about 3% by weight C₄ to C₁₄multiolefin monomer and from about 5% to about 10% by weight styrenicmonomer.
 26. The process defined in claim 16, wherein the halogenatingagent comprises bromine.
 27. The process defined in claim 16, whereinthe halogenating agent comprises chlorine.
 28. The process defined inclaim 16, wherein the halogenating agent is used in an amount to providea residual halogen content in the range of from about 0.1 to about 8% byweight of the polymer.
 29. The process defined in claim 28, wherein thehalogenating agent is used in an amount to provide a residual halogencontent in the range of from about 0.5 to about 4% by weight of thepolymer.
 30. The process defined in claim 29, wherein the halogenatingagent is used in an amount to provide a residual halogen content in therange of from about 1.5 to about 3% by weight of the polymer.